RPD Review Questions
Incorrect. A rest on #20 would be a primary rest, not an indirect retainer.
Incorrect. Tooth #21 would often have a rest on it and this rest would function as an indirect retainer. However, it would not be the MOST EFFECTIVE indirect retainer.
Incorrect. This tooth would seldom have a rest in the partially edentulous situation shown. Even if it did, it would not be the MOST EFFECTIVE indirect retainer.
Correct. The rest on #27 would be a very effective indirect retainer because it lies furthest from a line connecting the tips of the direct retainers (clasps).